The present invention relates generally to the field of telephones and more particularly to telephones controlling the volume of an alert.
Telephones have a ringing tone or other user alert sound that indicates when there is an incoming call. In some telephones the volume of the ringing tone is adjustable so that it can be audible in different environments having different noise levels.
One type of telephone that has an adjustable volume of the ringing tone is shown in European patent application EP 0 507 482 A2. European patent application EP 0 507 482 A2 discloses a telephone in which a circuit detects the level of an ambient noise signal and produces a detection signal responsive to the ambient noise signal. The detection signal is then used to produce a control signal that controls the ringing tone volume.
The above-described technique for controlling ringing tone volume suffers from a disadvantage. If the telephone is kept in a depository like a briefcase or in the pocket of a coat or jacket, the ringing tone will not be audible. This problem occurs because the ringing tone volume will be adjusted to a low level based on the low ambient noise in the depository.
The present invention solves the above described problem by controlling the volume of a device""s user alert sound based on an analysis of the device""s environment. In one embodiment, the device emits a sound and receives a resulting reflected sound. A processor measures characteristics such as the amplitude and/or delay of the reflected sound to determine the type of environment in which the device is located. The volume of the user alert sound is then adjusted based on the type of environment indicted by the characteristics of the reflected sound. For example, if the characteristics indicate a closed environment such as a brief case, the volume is adjusted to a high level, and if the characteristics indicate an open environment such as a desk top, the volume is adjusted to a low level.